Cristiano Ronaldo scored from the spot as Juventus won 2-1 at Roma to go top of Serie A.
The victory takes the reigning champions two points clear of Inter Milan, who were held to a 1-1 draw by Atalanta on Saturday, at the halfway stage of the season.
Merih Demiral put the visitors in front in the third minute and Ronaldo fired home a penalty after Paulo Dybala was brought down in the box, doubling their advantage with just 10 minutes played.
It was Ronaldo's 14th league goal of the season and ninth in his last six Serie A appearances.
Demiral had to go off after landing heavily on his knee, while winger Nicolo Zaniolo was carried off on a stretcher in tears after falling awkwardly.
Roma pulled a goal back on 68 minutes through a Diego Perotti spot-kick but were unable to find a leveller.
Sampdoria came from behind to storm to a 5-1 victory over fellow strugglers Brescia, while Giuseppe Iachini picked up his first win in charge of Fiorentina, winning 1-0 over bottom club SPAL, and Torino beat Bologna 1-0.
Goodnight ✨⚜️#ForzaViola 💜 #Fiorentina pic.twitter.com/4VHdFC3vKs — ACF Fiorentina English 🧢 (@ACFFiorentinaEN) January 12, 2020
Elsewhere, Udinese were 3-0 winners over Sassuolo, while Verona triumphed 2-1 against Genoa at the Stadio Marc'Antonio Bentegodi, where kick-off was put back by 15 minutes to enable the groundsman to re-draw the lines around the penalty area after referee Maurizio Mariani decided they were not straight.
Neymar scored twice but Ligue 1 leaders Paris St Germain had to settle for a point in 3-3 draw against Monaco at the Parc des Princes.
The Brazilian struck a third-minute opener before goals from Gelson Martins and Wissam Ben Yedder completed a six-minute turnaround for the visitors.
Fode Ballo-Toure's own-goal and Neymar's second from the penalty spot then handed PSG a half-time lead, but Islam Slimani made it 3-3 after 70 minutes to deny the champions victory.
A point leaves Thomas Tuchel's side five points clear of closest challengers Marseille with one game in hand.
Nantes registered their first win at Saint-Etienne in 19 years in a match played behind closed doors at the Stade Geoffroy-Guichard following the pyrotechnics that marred the end of their match against PSG in December, prevailing 2-0.
In Ligue 1's remaining fixture on Sunday, Dijon triumphed 1-0 over Lille in a match that saw both sides finish with 10 men.
